Electric switchboard.



a M d Du t .nm c e D L., L E N N U B H. L .au 4 8, 4 4 ,Ru va N M. T. BUNNELL, Executrix. ELECTRIC SWITCHBUARD.

(Apphctinn med Nov. 18, 1899.)

(No Model.)

@NNN LN E C @@JQ -UNITED STATES PATENT OFFICE.

MARY T. BUNNELL, OF NEW YORK, N. Y., EXECUTRIX OF JESSE II.

i BUNNELL, DEOEASED.

ELECTRIC SWITCHBOARD.

SPECIFICATION forming part of Letters Patent No. 644,844, dated March 6, 1900.

Application filed November 18, 1899. Serial No. 73 7,402. (No model.)

To tu whom t may concern:

Be it known that .lnssn H. BUNNELL, deceased, late a citizen of the United States, residing at New York, borough of Brooklyn, county of Kings, and State of New York, did invent certain new and useful Improvements in Electric Switchboards, of which the following is a specification.

This invention is directed particularly to an improvement upon electric switchboards like that disclosed in United States Patent No. 229,672, granted to Chas. E.Ohinnock on the 6th day of July, 1880; and it has forits object to provide a switchboard of the type referred to in which more perfect circuit connections may be effected between the individual cross-bars of the board through the agency of metallic switch-plugs like those disclosed in the aforesaid patent, and the improvement will be fully understood by referring to the accompanying drawings, in which- Figure l is a plan view of an entire switchboard, and Fig. 2 is a similar plan view of the reverse side of the board. Fig. 3 is a transverse sectional View taken through Fig. l on the line c :o and as seen looking thereat from the bottom toward the top of the drawings in the direction of the arrows; and Fig. 4 is a similar sectional view of a modified form of the invention, making it applicable for use in connection with very large central-station switchboards.

The switchboard disclosed in the patent granted to Chas. E. Chinnock, above referred to, embraces a series of metallic cross plates or bars secured to an insulating-base, one set of .said bars being provided with switch-plug holes and the other set thereof with laterallylocated flexible metallic strips, secured thereto by bolts and in the path of the entering ends of the switch-plugs. With such a switchboard there is a possibility of imperfect circuit connections between the iieXible metallic strips and the cross-bars to which they are secured; nor is it always possible to make good circuit connections between the cross-bars should the attendant fail to insert the switchplugs to their full depth. rl`he present improvement overcomes these defects by making the circuit connections directly between any pair of cross switch-bars by the metallic switch-plug itself and giving to the plug a firm mechanical and electrical connection between said plates by the agency of a strong spring located on one side of the entering end of the plug in such manner as to cause it to act upon the principle of a lever, with at least two of its points of support bearing firmly and laterally against the two interconnected switch-bars.

Referring now to the drawings in detail for a full and clear understanding of the invention, such as will enable others skilled in the art to use the same, B B B B represent the four sides of the usual insulating-base of the board, preferably of slate and held together by bolts g g, g g, F F F being insulating-feet on the under side of the board for securing it to a wall or partition.

l 2 3 4 5 6 7 represent one set of metallic switch-bars having their ends secured by bolts to the sides B B', and 8, 9, l0, il, l2, 13, and 14 the other set of metallic switch-bars having their ends secured to the sides B B by bolts g g', &c., said switch-bars being provided with the usual plug-holes in alinement with each other for the insertion of the switchplugs P/ l?2 P3 P4 P5 PG P7, the heads of said posts secured to the ends of one set of the switch-bars, and bs, b9 to b, inclusive, represent similar binding-posts secured to the ends of the other set of switch-bars. To the under surface of the lower set of switch-bars 8 9 10 l1, e., is secured by screws s a series of strong double springs S, so located that their upwardly-curved yielding ends lie directly in the path of the switch-plugs before insertion and in such manner that when inserted they will cause said switch-plugs to be rmly held against the two switch-bars, which they connect by lateral pressure, thus insuring always an absolutely-perfect electrical connection between any pair of bars where a switch-plug may be inserted. By thus arranging the switch-bars so that the electrical connection is direct from one bar to another through the interconnecting conducting switch plug p IOO and by causing said plug to assume the function of a lever which is so fulcrumed as to bear frictionally and laterally against the two interconnected switch-bars an absolutely-sure electrical connection is always effected, and by utilizing the springs S solely from a mechanical point of View the defect which is attributable to the springs in the before-mentioned Chinnock patent is avoided.

. In Fig. 4 of the drawings is illustrated in sectional view a modified form of the invention applicable to switchboards such as are used in large telephone and telegraph stations, where the lower cross-bars S to 14, inclusive, of Fig. 1 are done away with and a series of short individual metallic bars 10 102V 103 are substituted therefor and all secured to a slate or other insulating-board B2 by screws extending downwardly through them and through the springs S in to metallic sleeves t, the lower ends of which constitute shoulders for metallic binding-screws d, to which the individual conductors (not shown) are secured. In other words, with this form of the invention each individual conductor will be secured to its particular metallic sleeve t by the binding-screw d, and the metallic crossbars 1 to 7, inclusive, will be provided with their usual binding-posts b', h2 to 67, inclusive, as shown in Fig. 1. The circuit connection between any cross-bar 1 to 7, inclusive, an'd its corresponding short cross-bar 10 102 103 is effected by the switch-plug p in the same manner as the circuit connection was effected between the two sets of cross-bars illustrated in Fig. 1.

The present improvementis not limited to the especial details of construction herein shown and described for effecting a good electrical connection between the metallic crossbars of a switchboard, as it is believed that the invention is broad enough to include a switchboard having metalliccross-bars or metallic switch-bars in which the circuit connection is effected directly by the action of a switch-plu g held laterally against the switchbars which it is designed to unite by any medium which causes the switch-plug to act upon the principle of a lever, so as to assure actual conducting contact betweenV the plug and the bars when it (the plug) is once inserted, and the claims hereinafter made are directed generically to the broad application of this principle.

Having thus described the invention, what is claimed, and what it is desired to secure by Letters Patent of the United States, is-

1. Aswitchboard havingconductingswitchbars and one or more conducting switch-plugs adapted to make electrical contact directly between the bars; in combination with springs adapted to exert lateral pressure against the plugs in such manner as to cause them to bear frictionally and laterally against both of the interconnected bars.

2. Aswitchboardhavingconductingswitchbars and one or more conducting switch-plugs adapted to make electrical contact directly between the bars; in combination with springs secured to one set of said bars and adapted to exert lateral pressure against the plugs in such manner as to cause them to bear frictionally and laterally against both ofthe interconnected bars.

3. Aswitchboardhavingconductingswitchbars provided with plug-holes in alinement with each other; in combination with switchplugs and springs secured to one set of the switch-bars in such manner as to exert lateral pressure against the switch-plugs, when in position, and cause them to bear frictionally and laterally against both of the interconnected bars.

4. A switchboard having conducting switchbars provided with plug-holes in alinement with each other; in combination with switchplugs and double springs S secured to' the under surface of the lower set of switch-bars and with their upturned ends in alinement with the plug-holes and adapted, when t-he plugs are in position, to cause the same to bear frictionally against the interconnected bars.

5. A switchboard consisting of two sets of metallic cross-bars 1 to 7 inclusive and 8 to 14 inclusive, having their opposite ends secured to an insulating base or frame and provided With plug-holes in alinement with each other; in combination with switch-plugs P P2,

&c. having conducting partsp, together with double springs S secured to the under surface of the lower set of switch-bars with their upturned ends in alinement with the plugholes, the arrangement being such that when the switch-plugs are in position the springs cause them to act upon the principle of a lever and eXert strong frictional bearing against the interconnected bars, substantially as described.

In testimony whereof I have hereunto subscribed my name this 28th day of October, 1899.

MARY T. BUNNELL, Executrix of the @Sfr/.fe ofJesse H. Enamel?, de-

ceased.

Witnesses:

ALBERT WISE, EDITH BUNNELL. 

